Devices and methods for performing in-vivo imaging of passages or cavities within a body are known in the art. Such devices may include, inter alia, various endoscopic imaging systems and devices for performing imaging in various internal body cavities.
Reference is now made to FIG. 1 which is a schematic diagram illustrating an embodiment of an autonomous in-vivo imaging device. The device 10A typically includes an optical window 21 and an imaging system for obtaining images from inside a body cavity or lumen, such as the GI tract. The imaging system includes an illumination unit 23. The illumination unit 23 may include one or more light sources 23A. The one or more light sources 23A may include a white light emitting diode (LED), or any other suitable light source, known in the art. The device 10A includes a CMOS imaging sensor 24, which acquires the images and an optical system 22 which focuses the images onto the CMOS imaging sensor 24.
The optical system 22 may include one or more optical elements (not shown), such as one or more lenses (not shown), one or more composite lens assemblies (not shown), one or more suitable optical filters (not shown), or any other suitable optical elements (not shown) adapted far focusing an image of the GI tract on the imaging sensor as is known in the art and disclosed hereinabove with respect to the optical unit 22 of FIG. 1. The optical system 22 may be attached to, or mounted on, or fabricated on or disposed adjacent to the imager light sensitive pixels (not shown) as is known in the art.
The illumination unit 23 illuminates the inner portions of the body lumen or body cavity (such as, for example the gastrointestinal cavity) through an optical Window 21. Device 10A further includes a transmitter 26 and an antenna 27 for transmitting image signals from the CMOS imaging sensor 24, and one or more power sources 25. The power source(s) 25 may be any suitable power sources such as but not limited to silver oxide batteries, lithium batteries, or other electrochemical cells having a high energy density, or the like. The power source(s) 25 may provide power to the electrical elements of the device 10A.
Typically, in the gastrointestinal application, as the device 10A is transported through the gastrointestinal (GI) tract, the imager, such as but not limited to the multi-pixel CMOS sensor 24 of the device 10A acquires images (frames) which are processed and transmitted to an external receiver/recorder (not shown) worn by the patient for recording and storage. The recorded data may then be downloaded from the receiver/recorder to a computer or workstation (not shown) for display and analysis. During the movement of the device 10A through the GI tract, the imager may acquire frames at a fixed or at a variable frame acquisition rate. For example, the imager (such as, but not limited to the CMOS sensor 24 of FIG. 1) may acquire images at a fixed rate of two frames per second (2 Hz). Other different frame rates may also be used, depending, inter alia, on the type and characteristics of the specific imager or camera or sensor array implementation that is used, and on the available transmission bandwidth of the transmitter 26. The downloaded images may be displayed by the workstation by replaying them at a desired frame rate. This way, the expert or physician examining the data is provided with a movie-like video playback, which may enable the physician to review the passage of the device through the GI tract.
Typically, the device 10A or a similar autonomous in vivo imaging device is propelled through the GI tract by the natural action of peristalsis. When the device 10A or a similar autonomous in vivo imaging device is used for imaging, some of the acquired images may be out of focus. Additionally in some of the acquired images, a part or parts of the acquired image may be out of focus because of a possibly limited depth of field obtainable by the optical system 22. For example, if the optical system 22 includes a lens (not shown in detail) having a limited depth of field, and the imaged object (such as, for example, the wall of the GI tract) or a portion thereof was not disposed at a distance which is Within the depth of field range of the lens, the acquired image or parts thereof may be blurred or not depicted sharply.
It may therefore be desirable to decrease the number or the percentage of acquired images which are not acceptably focused or which have a reduced sharpness or detail due to out of focused imaging.